Why are my hard boiled egg yolks dark yellow and shiny?

What's wrong with dark yellow and shiny? If your eggs are dried out they were cooked too long or too hot.

Yes, mainecook61 is right. I always thought it was because the egg "dried out" a bit during aging, pulling the white away from the shell. But Harold McGee says that very fresh eggs have a relatively low albumen pH, causing it to adhere to the eggshell membrane. After a few days, the pH rises. He says that a little baking soda in the water can help fresh eggs to peel, but I've never tested it, because he also says that it increases the sulfur flavor that eggs can have.

However, if your farm raised eggs are very very fresh, peeling them will make you tear you hair out because the shells won't come away easily. A week old egg (which is still very fresh--store eggs are older) will be much easier to peel. Believe me, I have wept tears of frustration (or, alternatively, cursed my Leghorn and Buff hens) over a pan full of perfectly cooked eggs (Pierino's method, although a 15 minute wait seems to work for me) because the shells would not come away.

How to prepare hard cooked eggs; you don't actually boil them. Place eggs covered in a deep pan covered in cold water. Bring it just to the boil and then turn it off and remove from heat for 18 minutes. Your eggs are now done. You might want to roll them on the counter to make them easier to peel. I like to use good local farm raised eggs. The color of the yolk can be vivid. That's a good thing because they taste better.

Is there a gray edge on the yolks? That is overcooked. If they are shiny like wet that can be undercooked. I feel your pain I loath making hard boiled eggs. Here is a basic recipe that seems to work ok for me http://www.foodnetwork.com/recipes/ina-garten/hard-boiled-eggs-recipe/index.html

It sounds like eggs cooked to the correct time and temperature (rather than overcooked) to me.